Aspen trees, also known as Populus tremuloides, ultimately grow to 50 to 100 feet tall. They are found in cooler regions of the United States that have a definite winter season. A common place to find aspen trees is in Colorado. Pruning weaker growth off aspen trees allows the stronger growth more nutrients and produces a healthier, more robust tree. It is fairly easy to trim aspen trees, and only a few tools are required to complete this task.
Remove anything from under the aspen tree that could be damaged by falling limbs. Carefully walk around the tree and figure out which limbs will need to be pruned off.
Prune off any dead or diseased branches before pruning off live growth.
Start with the lower limbs and make an undercut on the branch 1 foot from the trunk. Use a pruning saw to cut through the bark and slightly into the wood.
Cut through the branch with a pruning saw 2 inches further out from the undercut from the top down.
Saw the remaining stub off from the top down just outside of the bark ridge. The ridge is where the branch slopes away from the trunk.
Continue to prune off the desired branches. Ideally, remove only 10 to 20 percent of the live branches each season, however you can remove up to 1/3 of the live branches if necessary. This amount should never be exceeded.